Abstract

Cyanotis axillaris, an annual succulent weed in the family Commelinaceae, was taken in this experiment to explore its allelopathic potential as plant allelopathy is considered as a biological option to control weeds. The aqueous methanol extracts of C. axillaris were applied on the growth of four dicotyledonous (cress, lettuce, alfalfa and rapeseed), and four monocotyledonous (barnyard grass, Italian ryegrass, timothy and foxtail fescue) test plant species at six different concentrations. The C. axillaris extracts inhibited the shoot and root growth of all test plant species, and such inhibition increased with increasing extract concentrations. Cress and lettuce showed complete growth inhibition at the concentration of 0.1 g dry weight equivalent extract/ml, whereas alfalfa, rapeseed, barnyard grass, Italian ryegrass, timothy and foxtail fescue showed growth inhibition greater than 50% of the control growth. At a concentration of 0.3 g dry weight equivalent extract/ml of C. axillaris extracts, cress, lettuce, alfalfa and rapeseed showed complete growth inhibition and that inhibition was greater than 30% of the control growth for barnyard grass, Italian ryegrass, timothy and foxtail fescue. Comparing the required concentration for 50% growth inhibition, lettuce was more susceptible and timothy was less susceptible with the extracts. Results indicate that C. axillaris may have allelopathic activity and may contain growth inhibitory substances. Therefore, C. axillaris could be a potential candidate to develop environment-friendly bio-herbicides for weed control.